Final answer:
An atom needs to achieve a full octet of electrons. Carbon, being in Group 14, has four electrons in its outer shell and can form up to four single covalent bonds to fulfill its octet.
Step-by-step explanation:
The number of single covalent bonds an atom can form is determined by how many more electrons it needs to reach a full octet (total of eight valence electrons). For example, a carbon atom (in Group 14 of the periodic table) has four electrons in its outermost shell and thus needs four more electrons to achieve an octet. This is achieved through the formation of four covalent bonds, as carbon is interested in forming substances where it can make four bonds to other atoms. Therefore, the answer to "This atom can form up to _____ single covalent bond(s)" is C. 4.